Flexible filter element having an end outlet

ABSTRACT

The present description provides a filter element that includes an end or side portion attached breather tube. One exemplary filter element described herein includes filter media having front and rear walls each including a proximal end and a distal end, a side portion at the proximal ends of the front and rear walls, and an outlet. The filter element further includes a breather tube attached to the filter media in fluid communication with the outlet. The outlet is positioned at least partially on the side portion, and the front and rear walls of the filter media are joined together at least partially along a perimeter.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage filing under 35 U.S.C. 371 ofPCT/US2016/018373, filed Feb. 18, 2016, which claims the benefit of U.S.Provisional Application No. 62/121,966, filed Feb. 27, 2015, thedisclosure of which is incorporated by reference in its/their entiretyherein.

TECHNICAL FIELD

The present description relates to a filter element of a respiratoryprotection device, and in particular, a flexible filter elementincluding an outlet near an end of the filter element.

BACKGROUND

Respiratory protection devices commonly include a mask body and one ormore filter elements attached to the mask body. The mask body is worn ona person's face, over the nose and mouth, and may include portions thatcover the head, neck, or other body parts in some cases. Clean air ismade available to a wearer after passing through filter media of thefilter element. In negative pressure respiratory protection devices, airis drawn through a filter element by a negative pressure generated by awearer during inhalation. Air from the external environment passesthrough the filter medium and enters an interior space of the mask bodywhere it may be inhaled by the wearer.

Various techniques have been used to construct and attach filterelements to a respirator. Filter elements are commonly connected to aninlet port of a mask body via a threaded engagement, bayonet engagement,or other engagement, for example. In the case of dual filter elementrespiratory protection devices, in which two filter elements areprovided to filter air for a wearer, the filter elements are oftenconnected to air inlets located proximate each cheek portion of themask, away from a central portion of the mask, such that the filterelements extend outward at sides of the wearer's head.

SUMMARY

The present description provides a filter element including filter mediahaving front and rear walls each having a proximal end and a distal end,a side portion at the proximal ends of the front and rear walls, and anoutlet, and a breather tube attached to the filter media in fluidcommunication with the outlet. The outlet is positioned at leastpartially on the side portion, and the front and rear walls of thefilter media are joined together at least partially along a perimeter.

The present description further provides a filter element includingfilter media having front and rear walls each having a proximal end anda distal end, a side portion at the proximal ends of the front and rearwalls, and an outlet, and a breather tube attached to the filter mediain fluid communication with the outlet. The filter media comprises asingle folded filter media portion that forms the front wall and therear wall, and the front and rear walls are joined at least partiallyalong a perimeter.

The present description further provides a filter element includingfilter media having front and rear walls each having a proximal end, adistal end and a perimeter, a side portion at the proximal ends of thefront and rear walls, and an outlet positioned at least partially on theside portion. The filter element further includes a plenum between thefront and rear walls of the filter media, and a breather tube adhesivelyjoined to the filter media in fluid communication with the outlet. Thefilter media includes a single folded filter media portion joined atleast partially along a perimeter and forming the front wall and therear wall and wherein the filter media is sealed around the outlet.

The above summary of the present invention is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. The Figures and the Detailed Description, which follow, moreparticularly exemplify illustrative embodiments.

BRIEF DESCRIPTION OF DRAWINGS

The present description will be further explained with reference to theappended Figures, wherein like structure is referred to by like numeralsthroughout the several views, and wherein:

FIG. 1 is a perspective view of an exemplary respiratory protectiondevice including a filter element according to the present description.

FIG. 2 is a perspective view of an exemplary filter element according tothe present description.

FIG. 3 is a cross-sectional view of an exemplary filter elementaccording to the present description.

FIG. 4 is a perspective view of exemplary filter media cut for assemblyaccording to the present description.

FIG. 5 is an exploded perspective view of an exemplary filter elementaccording to the present description.

While the above-identified figures set forth various embodiments of thedisclosed subject matter, other embodiments are also contemplated. Inall cases, this description presents the disclosed subject matter by wayof representation and not limitation. It should be understood thatnumerous other modifications and embodiments can be devised by thoseskilled in the art which fall within the scope and spirit of theprinciples of this description.

DETAILED DESCRIPTION

The present description provides a filter element that may be used witha respiratory protection device to provide breathable air for a user.The filter element includes filter media having front and rear walls anda breather tube attached to the filter media at an end or side portionof the filter media. A filter element as described herein may be easilysecured to a respiratory protection device in an ergonomic position.

FIG. 1 shows an example of a respiratory protection device 10 and filterelement 100. Respiratory protection device 10 may be positioned at leastpartially over a user's nose and/or mouth to provide breathable air to awearer. Respiratory protection device 10 includes a mask body 12including first and second inlet ports 13 and 14. First and second (notshown) filter elements 100 may be positioned on opposing sides of maskbody 12 and filter air received from the external environment before theair passes into an internal volume within the mask body for delivery toa wearer.

Mask body 12 may include a relatively more rigid or semi-rigid portion12 a and a compliant face contacting portion 12 b. Compliant facecontacting portion 12 b is compliantly fashioned for allowing the maskbody to be comfortably supported over a person's nose and mouth and/orfor providing an adequate seal with the face of a wearer to limitundesirable ingress of air into an interior of mask body 12, forexample. Face contacting member 12 b may have an inturned cuff so thatthe mask can fit comfortably and snugly over the wearer's nose andagainst the wearer's cheeks. Rigid or semi-rigid portion 12 a providesstructural integrity to mask body 12 so that it can properly supportbreathing air source components, such as filter elements 100, forexample. In various exemplary embodiments, mask body portions 12 a and12 b may be provided integrally or as separately formed portions thatare subsequently joined together in permanent or removable fashion.

An exhalation port 15 allows air to be purged from an interior spacewithin the mask body during exhalation by a wearer. In an exemplaryembodiment, exhalation port 15 is located centrally on mask body 12. Anexhalation valve is fitted at the exhalation port to allow air to exitdue to positive pressure created within mask body 12 upon exhalation,but prevent ingress of external air.

A harness or other support (not shown) may be provided to support themask in position about the nose and mouth of a wearer. In an exemplaryembodiment, a harness is provided that includes one or more straps thatpass behind a wearer's head. In some embodiments, straps may be attachedto a crown member supported on a wearer's head, a suspension for a hardhat, or another head covering.

First and second inlet ports 13, 14 are configured to receive first andsecond breathing air source components, such as filter elements 100. Inan exemplary embodiment shown in FIG. 1, mask body 12 includes first andsecond inlet ports 13, 14 on either side of mask body 12, proximatecheek portions of mask body 12 for example. First and second inlet ports13, 14 include complementary mating features (not shown) such thatfilter elements 100 may be securely attached to mask body 12. Othersuitable connections may be provided as known in the art, and in someexemplary embodiments mask body 12 may include only a single inlet portor may include more than two inlet ports, for example. The matingfeatures may result in a removable connection such that filter elements100 may be removed and replaced at the end of service life of the filterelement, or if use of a different breathing air source component isdesired. Alternatively, the connection may be permanent such thatbreathing air source components cannot be removed without damage to thebreathing air source component, for example.

In various embodiments, filter element 100 may be used with respiratoryprotection devices that may include a half face mask, full face mask,single inlets and/or multiple inlets. Similarly, filter element 100 maybe used with powered-air respiratory protection devices, or othersuitable devices.

FIGS. 1 through 3 show an exemplary filter element 100 including filtermedia 110 having a front wall 111, a rear wall 112, and an outlet 115(FIG. 3), and a breather tube 120 attached to filter media 110. Filterelement 100 includes first and second ends 101, 102, and breather tube120 is positioned proximate first end 101. In an exemplary embodiment,front and rear walls 111, 112 of filter media 110 include proximal ends111 a, 112 a, and distal ends 111 b, 112 b. Filter media 110 includes aside-portion 114 at proximal ends 111 b, 112 b. In various exemplaryembodiments, side portion 114 may include a side wall that extendssubstantially transverse to front and rear walls 111, 112, and/or may bean interface where front and rear walls 111, 112 meet.

Front and rear walls 111, 112 are fluid permeable and function as fluidinlets, such that air may enter an internal volume 117 of filter element100 after passing through filter media 110. Air may then flow to anoutlet 115 (FIG. 3), and exit through breather tube 120 to be deliveredto a user.

Front and rear walls 111, 112 include a perimeter 116. Filter media ofthe front and rear walls 111, 112, are joined along at least a portionof perimeter 116 such that leakage of air cannot occur between front andrear walls 111, 112. Front and rear walls 111, 112 may be joined alongat least a portion of perimeter 116, and in some exemplary embodimentsalong an entire perimeter 116, by a thermomechanical bond, such asultrasonic welding, sewing, adhesive bonding, other suitable methodsknown in the art or combinations thereof, such that air leakage betweenfront and rear walls 111, 112, is prevented. In an exemplary embodiment,front wall 111 and rear wall 112 are joined together directly around atleast a portion of perimeter 116. In other exemplary embodiments, frontwall 111 and rear wall 112 may be joined together indirectly via one ormore additional layers, such as a portion of a plenum 130 (FIG. 3), orother suitable layer(s) that allow a secure attachment and preventleakage. In an exemplary embodiment, a folded, single filter mediaportion forms front and rear walls 111, 112. Front and rear walls 111,112 may be joined along a portion of perimeter 116, and side portion 114includes the location of a fold of filter media 110, as described infurther detail herein. In other exemplary embodiments, front and rearwalls 111, 112 may be formed from first and second filter media portionsthat are subsequently joined together.

Outlet 115 allows fluid communication between internal volume 117 offilter element 100 and breather tube 120. In an exemplary embodiment,outlet 115 includes an opening through filter media 110. In otherexemplary embodiments, outlet 115 may be a location of filter media 110in fluid communication with breather tube 120, and/or may include feweror different layers of material than front and rear walls 111, 112, forexample. In the exemplary embodiment shown in FIG. 3, outlet 115includes an opening at least partially through side portion 114 offilter media 110. That is, outlet 115 is positioned near proximal ends111 a, 112 a of front and rear walls 111, 112, and may allow air flowfrom internal volume 117 through outlet 115 to breather tube 120 in adirection generally parallel to rear wall 112. In some exemplaryembodiments, outlet 115 includes an opening that is at least partiallythrough front wall 111, rear wall 112, and/or side portion 114. Anoutlet positioned near a proximal end of front and rear walls 111, 112,and at first end 101 of filter element 100, provides unique ergonomic,usability, and manufacturability features and advantages, as describedfurther herein.

In various exemplary embodiments, filter element 100 includes a plenum130 positioned between or contained within front and rear walls 111,112. Plenum 130 facilitates more even air flow through front and rearwalls 111, 112, and provides additional structure that resistscompression and assists in maintaining an internal volume 117 betweenfront and rear walls 111, 112.

Plenum 130 may be provided by any suitable component that is resistantto compression when a force is applied and/or acts to return filterelement 100 to an original shape after it has been compressed, folded,or otherwise acted on by an external force. In an exemplary embodiment,a nonwoven web of filaments can provide a suitable plenum. One suchexemplary plenum is described in U.S. Patent Publication Number2007/0144123, titled Filter Element that has Plenum Containing BondedContinuous Filaments. Alternatively, or in addition, other suitableplenums 130 may include a series of ribs, an internal frame, or othersuitable features or components to provide additional structure and/orresist compression of filter element 100.

Breather tube 120 may have any suitable shape and configuration suchthat filtered air may be delivered from filter element 100 to mask body12. In an exemplary embodiment, breather tube 120 includes one or moreattachment flanges 121, a nozzle 122 and a cantilever latch 123. One ormore attachment flanges 121 are attached to filter media 110 around aperimeter of outlet 115, and may include any suitable shape thatprovides a surface for attachment with filter media 110. In an exemplaryembodiment, attachment flange 121 includes front and rear flangeportions 121 a, 121 b joined to front and rear walls 111, 112 of filtermedia 110.

In an exemplary embodiment, breather tube 120 may provide a curvedrecess formed at least in part by attachment flanges 121 that sideportion 114 of filter media 110 may reside in. The curved recess may beshaped and sized to accommodate side portion 114 formed by foldingfilter media 110, as described further herein. A curved attachment endof breather tube 120 minimizes buckling and creasing, for example, whichcould otherwise occur when filter media 110 is joined to breather tube120.

Breather tube 120 may be attached to filter media 110 in any suitablematter that prevents leakage of air into or out of filter element 100.That is, air cannot enter the internal volume 117 without passingthrough filter media 110, when attached to a mask body 12 properlyfitted to a user's face. In various exemplary embodiments, breather tube120 may be joined to filter media 110 by an ultrasonic weld, adhesive,other suitable techniques, or combinations thereof. In an exemplaryembodiment, attachment flanges 121 of breather tube 120 are adhesivelyjoined to filter media 110, for example front wall 111, rear wall 112,and/or side portion 114. To facilitate bonding, and to prevent leakage,breather tube 120 may be adhesively bonded to filter media 110 at leastpartially at locations where individual layers of filter media 110 arejoined, for example by adhesive or ultrasonic welding such that thelayers of filter media 110 are bound together to prevent air fromentering internal volume 117 without passing through filter media 110.In an exemplary embodiment, attachment flanges 121 of breather tube 120are joined to outer surfaces of filter media 110. In other exemplaryembodiments, one or more attachment flanges 121 may be joined to aninner surface of filter media 110 such that filter media 110 partiallycovers breather tube 120.

In an exemplary embodiment, attachment flanges 121 provide relativelyrigid, external surfaces on opposing sides of filter element 100 thatmay be gripped by a user when handling filter element 100, such as whenattaching or releasing filter element 100 from mask body 12.

Breather tube 120 includes a nozzle 122 extending generally away fromfilter media 110. Nozzle 122 provides a passage for air to flow frominternal volume into mask body 12, and may engage a complementary shapedreceiver of mask body 12, for example. In an exemplary embodiment,nozzle 122 has a non-circular shape that prevents rotation when engagedwith a receiver of mask body 12, and may extend a relatively largelateral distance into a receiver of mask body 12 to allow a secureattachment. Nozzle 122 may extend outwardly generally linearly, or maycurve or otherwise exhibit a non-linear shape. Exemplary breather tube120 shown in FIGS. 1 through 3 includes a cantilever latch 123 thatinteracts with features of a receiver of mask body 12 to secure filterelement 100 to a mask body 12. In an exemplary embodiment, cantileverlatch 123 extends substantially parallel with nozzle 122. Uponinsertion, opening 124 of cantilever snaps to or mates with receiver 18to securely attach filter element 100 to mask body 12. Filter elementmay be removed by actuating release 17, for example, and removing filterelement 100 away from receiver 18. In an exemplary embodiment, breathertube 120 thus provides a sleeve-fit engagement between filter element100 and mask body 12. One such exemplary engagement is described in U.S.Pat. Pub. No. 2014/0216475, titled Sleeve Fit Respirator Cartridge.

Breather tube 120 may be formed of a suitable material to allow a secureconnection with mask body 12, for example, that is relatively more rigidthan filter media 110, and that is non-porous to prevent inadvertentleakage. In an exemplary embodiment, breather tube may be formed of apolypropylene. Other suitable materials include suitable polymers, othersuitable materials, and combinations thereof, and may be selected toprovide desired characteristics for a particular application or toappropriately interact with corresponding features of a mask body orother component of a respiratory protection device. In an exemplaryembodiment, breather tube 120 is a single, integrally formed component.In other exemplary embodiments, individual portions of breather tube120, for example, may be formed separately and subsequently joined orseparately attached to filter media 110 to provide desiredfunctionality. In some exemplary embodiments, breather tube 120 andplenum 130 may be integrally formed or joined together.

Filter media 110 may be made of any suitable material to provide desiredfiltration performance. In an exemplary embodiment, filter media 110includes a polypropylene blown microfiber web. In various exemplaryembodiments, filter material may include a nonwoven web, fibrillatedfilm web, air-laid web, sorbent-particle-loaded fibrous web, glassfilter paper, other suitable materials known in the art, andcombinations thereof. Filter media 110 may include polyolefins,polycarbonate, polyesters, polyurethanes, glass, cellulose, carbon,alumina, other suitable materials known in the art, and combinationsthereof. Filter media 110 may also include charged fibers configured toenhance filtration performance, active particulate, such as activatedcarbon or alumina, catalysts, or other reactive particulate.

In some exemplary embodiments, front and rear walls 111, 112 of filtermedia 110 may include or be encompassed by a cover web made from anysuitable woven or nonwoven material, such as spunbonded web, thermallybonded webs, or resin-bonded webs. A cover layer may be configured toprotect and contain other layers of filter media 110 and may serve as anupstream prefilter layer.

In an exemplary embodiment, filter media 110 is made of a non-rigid orflexible material. Accordingly, front and rear walls 111, 112 aregenerally non-rigid and flexible, such that front and rear walls 111,112 may flex or bend when contacted. In an exemplary embodiment, aperimeter 116 of front and rear walls 111, 112 may be slightly morestiff or rigid as compared to other portions of front and rear walls111, 112, but remain non-rigid and flexible such that filter media 110may bend and flex.

Filter media 110 may be cut to any suitable shape to provide a filterelement 100 having a desired shape, including triangular, rectangular,trapezoidal, oval, elliptical, or other suitable shape. In an exemplaryembodiment, filter element 100 is configured for ergonomic positioningon a mask body. Filter element 100 may be secured to mask body 12, orother respiratory protection component, such that filter element 100remains close to a user's head without substantially interfering with auser's field of vision, and allowing simultaneous use of other suitablepersonal protective equipment. In various exemplary embodiments, filterelement 100 may be characterized by a first angle (θ). First angle (θ)is an angle formed between a first longitudinal axis A passing through amiddle of filter media 110, and a second longitudinal axis B passingthrough a middle of nozzle 123 of breather tube 120. In variousexemplary embodiments, first angle (θ) is between about 180° and 120°,165° and 135°, or about 150°. Such angles facilitate connection withmask body 12 by a user, and ergonomic positioning of filter element 100when connected to mask body 12.

FIGS. 4 and 5 illustrate an exemplary method of making a filter elementas described herein. One exemplary method of making a filter elementaccording to the present description includes steps of cutting filtermedia to a desired shape and size, folding the filter media, joining theperimeter of the folded filter media, and attaching a breather tube atan end of the filter media.

Bulk filter media may be cut using any suitable technique known in theart to provide a filter media portion 210 having a desired shape andsize. In an exemplary embodiment, bulk filter media is cut into filtermedia portions 210 including outlet 215 and outer perimeter 216. Outlet215 comprises an opening 215 a and a sealed region 215 b where filtermedia portion 210 is sealed around opening 215 a. That is, in anexemplary embodiment, filter media portion 210 includes multiple layersof material. The multiple layers of material are sealed to preventleakage of air into an internal volume of the filter element withoutpassing through filter media portion 210 as desired. Sealed region 215 bmay be formed using ultrasonic welding, adhesive, other suitabletechniques known in the art, or combinations thereof.

Outer perimeter 216 may be shaped to allow filter media portion 210 tobe folded proximate the outlet to provide front and rear walls 211, 212and an outlet 215 positioned proximate a side portion 214 formed by thefold of filter media portion 210. In an exemplary embodiment, a plenumis provided within the filter media portion, and can be positionedbefore or after filter media portion 210 is folded and/or joined at aperimeter.

Folded filter media portion 210 may be joined along at least a portionof perimeter 216 to securely attach, directly or indirectly, front andrear walls 211, 212, and to define an internal volume 217 between frontand rear walls 211, 212, as shown in FIG. 5. In an exemplary embodiment,at least a portion of perimeter 216 of folded filter media portion 210is joined by discontinuous ultrasonic welding. Other suitable techniquesmay be used, including other thermomechanical techniques, such ascontinuous ultrasonic welding, sewing, adhesive bonding, other suitabletechniques known in the art, or combinations thereof, such that airleakage between front and rear walls 211, 212, is prevented.

Breather tube 220 is joined to filter media 210 to allow fluidcommunication with outlet 215. In an exemplary embodiment, engagementflanges 221 a, 221 b of breather tube 220 are adhesively joined tofilter media 210, for example front wall 211, rear wall 212, and sideportion 114. To facilitate bonding, and to prevent leakage, breathertube 220 is adhesively bonded to filter media 210 at least partially atsealed region 215 b.

A filter element as described herein may be manufactured in any suitablesequence of steps. In an exemplary embodiment, bulk media is prepared byforming a series of outlets 215, including sealed region 215 b, folded,and joined with a breather tube, such as breather tube 220. A plenum maythen be positioned between front and rear walls 211, 212, before joiningfront and rear walls 211, 212, and subsequently cutting from the bulkfilter media to provide a finished filter element. In various otherexemplary methods, the above steps may be provided in other sequences orcombinations to provide a filter element as described herein.

A filter element as described herein provides several unique featuresand advantages. Positioning of a breather tube at an end or side portionfacilitates easy and secure attachment of the filter element to a maskbody or respirator protection device. The filter element may be insertedand snapped into place, for example in a linear direction, withoutadditional rotation or positioning that may be associated with threadedor helical connections. This may be achieved while allowing filterelement to reside close to a user's head and minimizing interferencewith other personal protective equipment when secured to a mask body.Positioning of breather tube at an end or side portion providesadditional advantages in maximizing an effective filtering surface areaof front and rear walls because the breather tube does not usesubstantial space on these surfaces of the filter element.

A filter element as described herein provides further manufacturingadvantages by allowing a single filter media portion to form front andrear walls of the filter element, in various exemplary embodiments. Abreather tube as described herein may also be readily joined to filtermedia to provide a secure connection, allow easy handling by a user, andmay be configured for ergonomic connection with a desired mask body.

The present invention has now been described with reference to severalembodiments thereof. The foregoing detailed description and exampleshave been given for clarity of understanding only. No unnecessarylimitations are to be understood therefrom. It will be apparent to thoseskilled in the art that many changes can be made in the embodimentsdescribed without departing from the scope of the invention. Thus, thescope of the present invention should not be limited to the exactdetails and structures described herein, but rather by the structuresdescribed by the language of the claims, and the equivalents of thosestructures. Any patent literature cited herein is hereby incorporatedherein by reference in its entirety to the extent that it does notconflict with the description presented herein.

Any feature or characteristic described with respect to any of the aboveembodiments can be incorporated individually or in combination with anyother feature or characteristic, and are presented in the above orderand combinations for clarity only. That is, the present disclosurecontemplates all possible combinations, sequences, and arrangements ofvarious features of each of the exemplary embodiments and componentsdescribed herein, and each component may be combined or used inconjunction with any other component as may be desired for a particularapplication.

What is claimed is:
 1. A filter element, comprising: filter media havingfront and rear walls each comprising a proximal end and a distal end, aside portion at the proximal ends of the front and rear walls, and anoutlet, wherein the filter media comprises a single folded filter mediaportion that forms the front wall, the rear wall, and the side portion,and wherein the side portion interfaces between the front and rearwalls; and a breather tube attached to the filter media in fluidcommunication with the outlet, wherein the filter media defines aninternal volume enclosed by the front and rear walls such that airenters the internal volume through the filter media and exits throughthe breather tube to be delivered to a user; wherein the outlet ispositioned at least partially on the side portion, and the front andrear walls of the filter media are joined together at least partiallyalong a perimeter such that leakage of air cannot occur between thefront and rear walls, wherein the front wall and rear wall are joineddirectly together around less than the entire perimeter.
 2. The filterelement of claim 1, wherein the perimeter of the front and rear walls isnon-rigid.
 3. The filter element of claim 1, wherein the outletcomprises an opening through the side portion.
 4. The filter element ofclaim 1, wherein the outlet comprises an opening through the front wall.5. The filter element of claim 1, wherein the outlet comprises anopening through the rear wall.
 6. The filter element of claim 1, whereinthe outlet comprises an opening, and the opening does not pass throughthe front or rear walls.
 7. The filter element of claim 1, wherein thefront wall comprises a first filter media portion and the rear wallcomprises a second filter media portion, and the first and second filtermedia portions are at least partially joined together.
 8. The filtermedia of claim 1, wherein the filter media comprises multiple layers,and the outlet comprises a sealed region at which the multiple layersare sealed together.
 9. The filter element of claim 1, wherein thebreather tube is joined to outer surfaces of the front wall and the rearwall of the filter media.
 10. The filter element of claim 1, wherein thebreather tube is joined to an inner surface of the filter media.
 11. Thefilter element of claim 1, wherein the breather tube is adhesivelyjoined to the filter media.
 12. The filter element of claim 1, furthercomprising a plenum between the front and rear walls of the filtermedia.
 13. The filter element of claim 1, wherein the outlet isconfigured to allow air flow through the outlet to the breather tube ina direction generally parallel to the rear wall.
 14. The filter elementof claim 1, wherein the filter media defines a continuous portionforming the front and rear walls prior to joining the front and rearwalls of the filter media together at least partially along theperimeter.
 15. A filter element, comprising: filter media having frontand rear walls each comprising a proximal end and a distal end, a sideportion at the proximal ends of the front and rear walls, and an outlet;and a breather tube attached to the filter media in fluid communicationwith the outlet, wherein the filter media defines an internal volumeenclosed by the front and rear walls such that air enters the internalvolume through the filter media and exits through the breather tube tobe delivered to a user; wherein the filter media comprises a singlefolded filter media portion that forms the front wall, the rear wall,and the side portion, the side portion interfaces between the front andrear walls, and wherein the outlet is positioned at least partially onthe side portion, and the front and rear walls are joined at leastpartially along a perimeter such that leakage of air cannot occurbetween the front and rear walls, wherein the front wall and rear wallare joined directly together around less than the entire perimeter. 16.The filter element of claim 15, wherein the filter media defines acontinuous portion forming the front and rear walls prior to joining thefront and rear walls of the filter media together at least partiallyalong the perimeter.
 17. A filter element, comprising: filter mediahaving front and rear walls each comprising a proximal end, a distal endand a perimeter, a side portion at the proximal ends of the front andrear walls, and an outlet positioned at least partially on the sideportion; a plenum between the front and rear walls of the filter media;and a breather tube adhesively joined to the filter media in fluidcommunication with the outlet wherein the filter media defines aninternal volume enclosed by the front and rear walls such that airenters the internal volume through the filter media and exits throughthe breather tube to be delivered to a user; wherein the filter mediacomprises a single folded filter media portion joined at least partiallyalong a perimeter such that leakage of air cannot occur between thefront and rear walls and forming the front wall, the rear wall, and theside portion, wherein the filter media is sealed around the outlet, andwherein the side portion interfaces between the front and rear walls,wherein the front wall and rear wall are joined directly together aroundless than the entire perimeter.
 18. The filter element of claim 17,wherein the filter media defines a continuous portion forming the frontand rear walls prior to joining the front and rear walls of the filtermedia together at least partially along the perimeter.